Trying to understand
the clade Stylinodontidae can be difficult. Basal taxa are incomplete. I made mistakes earlier with less experience. Now that a little time has passed and experience gained, here (Fig 1) is the current lineup of taxa leading to Stylinodon, all to scale.
Vulpavus, from the Paleocene, is a proximal outgroup taxon. That taxon sheds light on the phylogenetic minaturization that attended the genesis of this clade, too.
It’s really remarkable just how often this generally overllooked hypothesis comes into play at the genesis of clades recovered in the LRT.
Figure 1. The clade of taxa leading to Stylinodon in the LRT. Vulpavus, from the Paleocene, is an outgroup taxon.
Schowalteria
is the phylogenetically miniaturized basalmost taxon in this Paleocene to Eocene clade. Note the shorter rostrum and larger orbit, traditional juvenile traits in placental mammals.
Wikipedia reports,
“Stylinodon is an extinct genus of taeniodont mammal, and is the best known, and last genus of taeniodonts, lived some 45 million years ago during middle Eocene in North America.” We looked at the paraphyly of the Taeniodonta several years ago.
References
wiki/Stylinodon
The Pterosaur Heresies 